The U.S. Navy utilizes underwater acoustic projectors for many purposes, such as for testing and calibrating surveillance equipment and other types of sound receiving equipment aboard surface ships or submarines. Prior acoustic projectors of the low frequency type have been relatively bulky and expensive, and since they have generally been of the mechanically resonant type they have not been capable of producing amplitude modulation and frequency modulation of their output signals at varying depths without having changes in any one of these variables being coupled to and hence producing resultant changes in one or more of the other variables. Prior art acoustic projectors of the low frequency type also have generally used various sorts of intricate drive mechanisms which rendered the projector expensive to manufacture, bulky, and inefficient.